Prime number/Citable Version

A prime number is a whole number (i.e, one having no fractional or decimal part) that cannot be evenly divided by any numbers but 1 and itself. The first few prime numbers are 2, 3, 5, 7, 11, 13, and so on. With the exception of 2, the first few numbers on this list are odd numbers, but not every odd number is prime. For example, $9=3\cdot 3$ and $15=3\cdot 5$, so neither 9 nor 15 is prime.